>The existing circuit uses energy dump open loop control - >they charge the inductor to a selected current and then >dump it and control the repetition rate. I believe this is essentially what Olin was proposing for the solar panel charger, but he was selecting a current that is close to saturation for the inductor. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist